120 / 1020
S98
ESTRO 35 2016
_____________________________________________________________________________________________________
Breathing motion was largest in the CC direction and more
prominent for more caudal LNs. Cardiac induced motion was
often (77%) largest in the AP direction (not shown) and
tended to be largest for more cranial LNs, occasionally (44 %)
being the dominant motion component. The daily baseline
shifts from all fractions resulted in interfraction motion
margins of 4.9mm(LR), 4.7mm(CC), and 6.4mm(AP).
Conclusion:
The motion of Visicoils in projection images of
daily CBCTs was used to map and analyze intrafraction and
interfraction motion of mediastinal LNs. While the motion
was governed by breathing induced motion, the most cranial
LNs had substantial cardiac induced motion.
* Van Herk et al. Errors and margins in radiotherapy. 2004
Symposium: Head and neck: reduction of margins and side
effects
SP-0216
Contouring of normal tissues in head and neck
radiotherapy
S. Hol
1
Dr. Bernard Verbeeten Instituut, Tilburg, The Netherlands
1
In the head and neck region, there are a lot of organs at risk
(OAR) to take into account when making a treatment plan.
The radiation fields are often very large and can go up to the
brain and down to the lungs. The OAR in this region are
responsible for a lot of body functions, like walking, talking,
swallowing and taste. Some of the OAR are parallel organs, so
they will be able to compensate the loss of part of the organ
and others are serial organs, which implies that the dose to
the entire organ has to be below a threshold value in order to
maintain the functionality.
In recent years most hospitals have started delineating more
OAR in the head and neck region, but for some, there is no
concensus on the constraints that have to be applied.
Recently, consensus guidelines for head and neck OAR
delineation were defined by Brouwer et al (1) To make sure
that in the future we will be able to define constraints for
these OAR we need a lot of data. This can only be obtained if
there is consensus among institutes on delineation and
reporting in the same manner.
In this presentation the different OAR will be discussed and a
short summary of recently published guidelines will be
provided.
(1) CT-based delineation of organs at risk in the head and
neck region: DAHANCA, EORTC, GORTEC, HKNPCSG, NCIC
CTG, NCRI, NRG Oncology and TROG consensus guidelines.
Brouwer, C. et al. Radiother. Oncol. 2015; 117: 83–90.
SP-0217
The ESTRO perspective - a guideline for positioning of head
and neck patients
M. Mast
1
Haaglanden Medical Centre Location Westeinde Hospi, Den
Haag, The Netherlands
1
, M. Leech
2
, M. Coffey
2
, F. Moura
3
, A. Ostavics
4
, D.
Pasini
5
, A. Vaandering
6
2
Trinity College Dublin, University of Dublin, Dublin, Ireland
Republic of
3
Hospital Cuf Descobertas, Radiotherapy, Lisbon, Portugal
4
General Hospital Vienna AKH Wien, Radiotherapy, Vienna,
Austria
5
Policlinico Universitario Agostino Gemelli, Radiotherapy,
Rome, Italy
6
UCL Cliniques Univ. St.Luc, Radiotherapy, Brussels, Belgium
Purpose:
These guidelines have been developed to assist
Radiation TherapisTs (RTTs) in positioning, immobilisation,
position verification and treatment for head and neck cancer
(HNC) patients presenting for radiation therapy.
Methods and materials:
A critical review of the literature
was undertaken by the authors, searching relevant databases
including PubMed, Embase and Google Scholar. Search terms
used included combinations of and Boolean operations of
‘head and neck cancer’, ‘radiation therapy’, ‘radiotherapy’,
‘positioning’, ’immobilisation’, ‘verification’, ‘cone beam
CT’, and ‘electronic portal imaging’. Studies in English,
French, Portuguese, Italian and German were included. Based
on the literature review, a survey was developed to ascertain
the current positioning, immobilisation and position
verification methods for head and neck radiation therapy
across Europe. The survey consisted of 40 questions, divided
into 5 sections. The sections contained both open and closed
questions on: Demographics, Patient Positioning,
Immobilisation devices, CT/Simulation Practice, Position
Verification as well as elements of quality assurance (QA) in
relation to positioning and immobilisation. Data analysis was
performed using SPSS Statistics version 20.0 (IBM SPSS
Statistics for Windows. Armonk, NY: IBM Corp.). Descriptive
statistics were calculated and appropriate figures and tables
constructed. Cross tabulations were performed where
appropriate to maximise data analysis.
Results:
Results from the European-wide survey indicated
that a wide variety of treatment practices and treatment
verification protocols are in operation for head and neck
cancer patients across Europe currently. These ranged from
3DCRT to VMAT and from daily online CBCT imaging to offline
correction protocols using kV EPIs or in some cases, MV portal
imaging. In terms of immobilisation, the majority of
respondents use thermoplastic masks in their immobilisation
of head and neck patients, with some variance in how
shoulder position is maintained. The full results from this
survey are available in the complete guideline document,
available on the ESTRO website. Guidelines were given for:
Positioning
prior
to
thermoplastic
mask
constructionConstruction of thermoplastic maskThe CT
procedureTreatment
Verification
and
deliveryMatch
Structures for Image Verification.
Conclusion:
The preparation of this guideline document has
demonstrated that although there have been substantial
changes in the set up, positioning, immobilisation and
verification of head and neck cancer patients over the last
number of years across Europe, significant variations still
exist. These variations can be attributed to differences in
resource type and quality, institutional protocols as well as
considerable differences in education level of radiation
therapy professionals across Europe. RTTs must be aware of
the potential dosimetric impact of poor positioning and
immobilisation and/or position verification procedures as
well as their influence on required margins for HNC radiation
therapy. These guidelines have been developed to provide
RTTs with guidance on positioning, immobilisation and
position verification of HNC patients. The guidelines will also
provide RTTs with the means to critically reflect on their own
daily clinical practice with this patient group.